The present invention relates to an air bag and an air bag apparatus which is applicable to a vehicle, for instance, an automobile, so as to deploy the air bag from a side of an occupant's seat along a side of an occupant on the seat.
Conventionally, there has been proposed a so-called side air bag apparatus for an automobile which is adapted to deploy an air bag on a side of an occupant in order to protect the occupant upon occurrence of side collision of the automobile. The air bag is installed in a folded state on a side of an occupant's seat and inflatable and deployable between the occupant and a door of the automobile so as to protect a side portion of the occupant. The side air bag apparatus includes a bag-shaped air bag and an inflator for supplying gas to the air bag. The air bag is formed into a flat bag shape by overlapping a pair of base clothes and sewing them together along outer peripheries thereof. However, when the thus-constructed air bag is deployed by supplying the gas thereto, the air bag is deformed into a spindle shape in section in which a central portion of the air bag has a maximum thickness and the outer peripheral portion thereof has a less thickness. In the air bag construction in which the thickness is locally varied when deployed, it is not always easy to deploy the air bag in a predetermined position in a stable state. Further, for the purpose of ensuring a protecting region in the air bag which has a predetermined thickness, namely, a predetermined impact-absorption stroke, to protect the occupant, it is required to construct an air bag that has a large shape in a side view by increasing the base clothes.
Japanese Patent Application First Publication No. 8-2364 describes a multi-cell air bag which is adapted to be deployed from a door side of an automobile, The air bag has a generally rectangular shape and includes multiple tubular air cells formed by a plurality of base clothes, each of which is curved into a U-shape in section. The U-shaped base clothes are overlapped with and sewed to one another to form the multiple tubular air cells aligned in a row. A pair of rectangular base clothes are sewed to upper and lower openings of the U-shaped base clothes to thereby form the rectangular box-shape. However, this sewing work is complicated and troublesome in view of cost saving. Further, the air bag inflatable from the door side has a gas introduction inlet on a planar portion of one of opposed side portions of the air bag at which the air bag is fixed to a door panel side of the automobile. When deployed, the air bag is not supported at only one end and the air bag can be readily and stably developed along a planar door panel. Thus, it will be unnecessary to consider stability of a deploying attitude of the air bag inflatable from the door side.
Japanese Patent Application First Publication No. 8-192712 describes an air bag that is formed by folding a rectangular base cloth at a centerline into halves, overlapping the halves each other and sewing them together along outer peripheries thereof to form a rectangular bag. Then, the rectangular bag is formed into a rectangular box-shaped air bag that has two opposed side portions and a peripheral portion between the opposed side portions, by tucking and sewing four corners of the rectangular bag. In the thus-formed box-shaped air bag, four corner portions thereof become stiff due to tucking, and a middle area of the peripheral portion becomes stiff along the seam line that extends in the middle area of the peripheral portion. On the other hand, ridges between the peripheral portion and the side portions are formed by simply folding and become relatively soft. The air bag, therefore, tends to be deployed in the form of a generally spindle shape in section. Similar to the above-mentioned conventional art, the air bag of this conventional art has a gas introduction inlet on a planar portion of one of the opposed side portions. Accordingly, it will be unnecessary to consider stability of a deploying attitude of the air bag of the conventional art. Further, in a modified air bag of the above conventional art, the gas introduction inlet is formed at one of the corner portions which is free from tucking. The modified air bag also has the seam line that extends in the middle area of the peripheral portion. Thus, the modified air bag is not constructed so as to stabilize the deploying attitude.
Japanese Patent Application First Publication No. 8-225054 describes a box-shaped air bag that includes two opposed main base clothes and a peripheral base cloth through which outer peripheries of the main base clothes are connected with each other. In the air bag of the conventional art, a gas introduction inlet is formed in one of the main base clothes which is attached to a door panel of an automobile. It will be unnecessary to consider stability of a deploying attitude of the air bag of this conventional art.